arch/i386/kernel/i8237.c

   1 /*
   2  * i8237.c: 8237A DMA controller suspend functions.
   3  *
   4  * Written by Pierre Ossman, 2005.
   5  */
   6
   7 #include <linux/init.h>
   8 #include <linux/sysdev.h>
   9
  10 #include <asm/dma.h>
  11
  12 /*
  13  * This module just handles suspend/resume issues with the
  14  * 8237A DMA controller (used for ISA and LPC).
  15  * Allocation is handled in kernel/dma.c and normal usage is
  16  * in asm/dma.h.
  17  */
  18
  19 static int i8237A_resume(struct sys_device *dev)
  20 {
  21         unsigned long flags;
  22         int i;
  23
  24         flags = claim_dma_lock();
  25
  26         dma_outb(DMA1_RESET_REG, 0);
  27         dma_outb(DMA2_RESET_REG, 0);
  28
  29         for (i = 0;i < 8;i++) {
  30                 set_dma_addr(i, 0x000000);
  31                 /* DMA count is a bit weird so this is not 0 */
  32                 set_dma_count(i, 1);
  33         }
  34
  35         /* Enable cascade DMA or channel 0-3 won't work */
  36         enable_dma(4);
  37
  38         release_dma_lock(flags);
  39
  40         return 0;
  41 }
  42
  43 static int i8237A_suspend(struct sys_device *dev, pm_message_t state)
  44 {
  45         return 0;
  46 }
  47
  48 static struct sysdev_class i8237_sysdev_class = {
  49         set_kset_name("i8237"),
  50         .suspend = i8237A_suspend,
  51         .resume = i8237A_resume,
  52 };
  53
  54 static struct sys_device device_i8237A = {
  55         .id     = 0,
  56         .cls    = &i8237_sysdev_class,
  57 };
  58
  59 static int __init i8237A_init_sysfs(void)
  60 {
  61         int error = sysdev_class_register(&i8237_sysdev_class);
  62         if (!error)
  63                 error = sysdev_register(&device_i8237A);
  64         return error;
  65 }
  66
  67 device_initcall(i8237A_init_sysfs);